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Question 1General Electrical Knowledge and National Electrical Code Structure

The National Electrical Code is organized into numbered chapters. Which chapter contains the requirements for wiring methods and materials?

  1. Chapter 3 Correct answer.
  2. Chapter 2
  3. Chapter 4
  4. Chapter 1

Explanation

Chapter 3 of the NEC is titled "Wiring Methods and Materials" and contains the articles governing conductors, raceways, and cables. Chapter 1 covers general provisions, Chapter 2 covers wiring and protection, and Chapter 4 covers equipment for general use.

Question 2General Electrical Knowledge and National Electrical Code Structure

In the NEC, the word "shall" indicates a requirement that is:

  1. recommended as good practice
  2. mandatory Correct answer.
  3. permitted but not required
  4. informational only

Explanation

Section 90.5 states that "shall" denotes a mandatory requirement and "shall not" denotes a mandatory prohibition. Permissive language in the Code is expressed with the word "may."

Question 3General Electrical Knowledge and National Electrical Code Structure

Ohm's law relates voltage (E), current (I), and resistance (R). Which equation is correct?

  1. E = I × R Correct answer.
  2. E = I ÷ R
  3. R = E × I
  4. I = E × R

Explanation

Ohm's law states that voltage equals current multiplied by resistance. The companion forms I = E/R and R = E/I follow directly from the same relationship.

Question 4General Electrical Knowledge and National Electrical Code Structure

The unit of electrical resistance is the:

  1. ampere
  2. coulomb
  3. volt
  4. ohm Correct answer.

Explanation

Resistance is measured in ohms, represented by the Greek letter omega. One ohm allows one ampere of current to flow when one volt is applied across it.

Question 5General Electrical Knowledge and National Electrical Code Structure

Article 100 of the NEC contains which information?

  1. A list of mandatory annexes
  2. Rules for grounding and bonding
  3. Definitions of terms used throughout the Code Correct answer.
  4. Ampacity tables for insulated conductors

Explanation

Article 100 in Chapter 1 defines terms that appear throughout the Code, and those definitions govern how the rules are applied. Ampacity tables appear in Article 310, and grounding rules appear in Article 250.

Question 6General Electrical Knowledge and National Electrical Code Structure

Which organization publishes the National Electrical Code, NFPA 70?

  1. National Electrical Manufacturers Association
  2. Underwriters Laboratories
  3. National Fire Protection Association Correct answer.
  4. International Association of Electrical Inspectors

Explanation

The NEC is NFPA 70, developed and published by the National Fire Protection Association through its consensus code-making process. Other organizations test products, train inspectors, or represent manufacturers but do not publish the Code.

Question 7General Electrical Knowledge and National Electrical Code Structure

The ampacity of a conductor is best described as its:

  1. insulation wall thickness
  2. current-carrying capacity under stated conditions Correct answer.
  3. maximum voltage rating
  4. cross-sectional area in circular mils

Explanation

Article 100 defines ampacity as the maximum current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. It depends on conductor size, insulation rating, and ambient conditions.

Question 8General Electrical Knowledge and National Electrical Code Structure

In a resistive DC circuit, electrical power is calculated as:

  1. P = E × I²
  2. P = E × I Correct answer.
  3. P = E ÷ I
  4. P = I ÷ E

Explanation

Power in watts equals voltage in volts multiplied by current in amperes. Combining this with Ohm's law produces the equivalent forms P = I²R and P = E²/R.

Question 9General Electrical Knowledge and National Electrical Code Structure

Which NEC article contains the requirements for branch circuits?

  1. Article 215
  2. Article 240
  3. Article 210 Correct answer.
  4. Article 220

Explanation

Article 210 sets the requirements for branch circuits, including ratings, receptacle outlet provisions, and GFCI and AFCI protection. Article 215 covers feeders and Article 220 covers load calculations.

Question 10General Electrical Knowledge and National Electrical Code Structure

Article 250 of the NEC covers:

  1. overcurrent protection
  2. grounding and bonding Correct answer.
  3. switches and receptacles
  4. general wiring methods

Explanation

Article 250 in Chapter 2 establishes the requirements for grounding and bonding of electrical systems and equipment. It addresses system grounding, equipment grounding conductors, and grounding electrode systems.

Question 11General Electrical Knowledge and National Electrical Code Structure

Which article provides the method for computing branch-circuit, feeder, and service loads?

  1. Article 230
  2. Article 210
  3. Article 220 Correct answer.
  4. Article 215

Explanation

Article 220 provides the calculation methods, including demand factors, used to determine branch-circuit, feeder, and service loads. The results are then used to size feeders, services, and overcurrent devices.

Question 12General Electrical Knowledge and National Electrical Code Structure

In a parallel circuit, which quantity is the same for every branch?

  1. current
  2. resistance
  3. voltage Correct answer.
  4. power

Explanation

In a parallel circuit all branches are connected across the same two points, so the voltage across each branch is identical. The total current is the sum of the individual branch currents.

Question 13General Electrical Knowledge and National Electrical Code Structure

Under Section 210.8(A), GFCI protection is required for receptacles installed in which dwelling-unit location?

  1. Closets
  2. Bedrooms
  3. Bathrooms Correct answer.
  4. Attics

Explanation

Section 210.8(A) requires ground-fault circuit-interrupter protection for receptacles in dwelling-unit bathrooms, garages, outdoors, crawl spaces, unfinished basements, and similar wet or damp locations. Bedroom receptacles fall under the arc-fault protection rules instead.

Question 14General Electrical Knowledge and National Electrical Code Structure

For equipment rated 600 volts or less, Condition 1, the minimum depth of the working space in front of the equipment is:

  1. 3 feet Correct answer.
  2. 30 inches
  3. 3 1/2 feet
  4. 4 feet

Explanation

Table 110.26(A)(1) requires a minimum depth of 3 feet for Condition 1, where exposed live parts on one side are not grounded and there are no live parts on the other side. Greater depths apply to Conditions 2 and 3 and to higher voltages.

Question 15General Electrical Knowledge and National Electrical Code Structure

Allowable ampacities for insulated conductors rated 0 through 2000 volts are found in which table?

  1. Table 430.52
  2. Table 310.16 Correct answer.
  3. Table 314.16(A)
  4. Table 250.122

Explanation

Table 310.16 lists allowable ampacities based on conductor size, insulation temperature rating, and the number of current-carrying conductors in the raceway or cable. Ambient temperature correction and conductor adjustment factors are applied afterward.

Question 16General Electrical Knowledge and National Electrical Code Structure

Which NEC article contains the general requirements for wiring methods and materials?

  1. Article 310
  2. Article 280
  3. Article 300 Correct answer.
  4. Article 250

Explanation

Article 300 sets the general requirements for wiring methods that apply throughout Chapter 3. The individual articles then add requirements specific to each method, such as conduit or cable.

Question 17General Electrical Knowledge and National Electrical Code Structure

The annexes to the National Electrical Code are:

  1. mandatory requirements equal in force to the chapters
  2. informational and not mandatory unless referenced in the body of the Code Correct answer.
  3. automatically superseded by any local amendment
  4. applicable only to industrial occupancies

Explanation

The annexes contain informational material such as calculation examples, reference tables, and recommended practices. They are not enforceable requirements unless a rule in the body of the Code specifically references them.

Question 18General Electrical Knowledge and National Electrical Code Structure

Table 1 in Chapter 9 is used to determine the:

  1. maximum percentage of conduit cross-sectional area occupied by conductors Correct answer.
  2. minimum bending radius for rigid metal conduit
  3. volume of a device box in cubic inches
  4. ampacity of conductors installed in raceways

Explanation

Chapter 9 Table 1 gives the maximum percentage of a raceway's internal cross-sectional area that conductors may occupy. It is applied together with the conductor dimension tables in Chapter 9.

Question 19General Electrical Knowledge and National Electrical Code Structure

Article 404 of the NEC provides requirements for:

  1. motors and controllers
  2. receptacles
  3. switches Correct answer.
  4. luminaire installation

Explanation

Article 404 covers switches, including their ratings, mounting, and location. Receptacles appear in Article 406 and luminaires in Article 410.

Question 20General Electrical Knowledge and National Electrical Code Structure

The scope of the National Electrical Code is described in which section?

  1. Section 110.1
  2. Article 100
  3. Section 90.2 Correct answer.
  4. Section 90.1

Explanation

Section 90.2 describes the scope of the Code, listing the installations covered and those expressly excluded. Section 90.1 states the purpose behind those requirements.

Question 21General Electrical Knowledge and National Electrical Code Structure

Under Section 240.4(D), the maximum overcurrent protective device rating permitted for 14 AWG copper conductors is generally:

  1. 15 amperes Correct answer.
  2. 25 amperes
  3. 30 amperes
  4. 20 amperes

Explanation

Section 240.4(D) limits overcurrent protection for small conductors, and 14 AWG copper is limited to 15 amperes unless a specific exception applies. These limits protect the conductor from overcurrent damage and are separate from its ampacity.

Question 22General Electrical Knowledge and National Electrical Code Structure

Article 430 of the NEC governs:

  1. motors, motor circuits, and controllers Correct answer.
  2. storage batteries
  3. air-conditioning and refrigerating equipment
  4. transformers

Explanation

Article 430 covers motors, motor circuits, and controllers, including conductor sizing, overload protection, and disconnecting means. Air-conditioning and refrigeration equipment has separate rules in Article 440.

Question 23General Electrical Knowledge and National Electrical Code Structure

Under Table 314.16(B), the volume allowance for each 12 AWG conductor in a box is:

  1. 2.50 cubic inches
  2. 2.25 cubic inches Correct answer.
  3. 2.00 cubic inches
  4. 1.50 cubic inches

Explanation

Table 314.16(B) assigns 2.25 cubic inches for each 12 AWG conductor, with larger allowances for larger sizes. The total volume of conductors, devices, and fittings must not exceed the box volume given in Table 314.16(A).

Question 24General Electrical Knowledge and National Electrical Code Structure

Under Article 500, a Class I location is one in which:

  1. ignitible fibers or flyings may be present
  2. flammable gases, vapors, or liquids are or may be present Correct answer.
  3. combustible dust may be present in quantities sufficient to produce explosive mixtures
  4. corrosive liquids are handled in open containers

Explanation

Article 500 defines Class I locations as those where flammable gases, vapors, or liquids are or may be present in quantities sufficient to produce ignitible or explosive mixtures. Class II covers combustible dust, and Class III covers ignitible fibers and flyings.

Question 25General Electrical Knowledge and National Electrical Code Structure

Section 90.3 explains that Chapters 5, 6, and 7 of the NEC:

  1. supplement or modify the requirements of Chapters 1 through 4 Correct answer.
  2. replace Chapters 1 through 4 for the occupancies they cover
  3. apply exclusively to industrial machinery
  4. are informational only and contain no requirements

Explanation

Section 90.3 provides that Chapters 5, 6, and 7 cover special occupancies, special equipment, and special conditions, and that they supplement or modify the general rules in Chapters 1 through 4. The general rules therefore continue to apply unless specifically modified.

Question 26General Electrical Knowledge and National Electrical Code Structure

The National Electrical Code is organized into nine chapters. Chapter 1 is titled:

  1. Wiring Methods and Materials
  2. General Correct answer.
  3. Wiring and Protection
  4. Equipment for General Use

Explanation

Chapter 1, titled General, contains Articles 100 and 110, which establish definitions and the general requirements that apply to electrical installations. The remaining chapters build on those fundamentals, with Chapters 2, 3, and 4 addressing wiring and protection, wiring methods and materials, and equipment for general use, respectively.

Question 27General Electrical Knowledge and National Electrical Code Structure

In a National Electrical Code rule, use of the word "shall" indicates:

  1. a mandatory requirement Correct answer.
  2. a permissive allowance
  3. an explanatory note
  4. a recommendation the installer may follow

Explanation

The NEC distinguishes mandatory rules from permissive rules by word choice: "shall" identifies a mandatory requirement that must be met, while "shall be permitted" identifies a permissive rule that allows an optional method. Explanatory material is presented separately in informational notes.

Question 28General Electrical Knowledge and National Electrical Code Structure

Requirements for the use and identification of grounded conductors are found in which NEC article?

  1. Article 210
  2. Article 225
  3. Article 200 Correct answer.
  4. Article 240

Explanation

Article 200, Use and Identification of Grounded Conductors, governs how grounded conductors are identified and used throughout an installation. It is one of several Chapter 2 articles that address specific conductor and circuit functions.

Question 29General Electrical Knowledge and National Electrical Code Structure

Article 100 defines "Listed" as equipment, materials, or services that are:

  1. recognized by the serving utility as meeting its service connection standards
  2. marked by the manufacturer as suitable for the specific installation
  3. examined and found acceptable by the electrical inspector during the rough-in inspection
  4. included in a list published by an organization acceptable to the AHJ Correct answer.

Explanation

Listing involves inclusion in a list published by an organization that is acceptable to the authority having jurisdiction, is concerned with product evaluation, and maintains periodic inspection of production. Listing is a third-party function and is distinct from field approval or manufacturer marking.

Question 30General Electrical Knowledge and National Electrical Code Structure

Section 300.3(B) generally requires that all conductors of the same circuit be:

  1. identified at both ends and at every junction point by phase and system
  2. installed only in raceways approved for use in wet locations of the building
  3. run together in the same raceway, cable, trench, or cable tray Correct answer.
  4. sized at not less than the ampacity of the overcurrent device protecting them

Explanation

Section 300.3(B) requires all conductors of the same circuit, including the equipment grounding conductor and any bonding conductor, to be contained within the same raceway, cable, trench, cord, or cable tray. Keeping circuit conductors together limits inductive heating and impedance in the circuit.

Question 31General Electrical Knowledge and National Electrical Code Structure

The ampacities given in Table 310.16 are based on an ambient temperature of ___ and ___ current-carrying conductors in a raceway or cable.

  1. 30 degrees C; not more than six
  2. 40 degrees C; not more than three
  3. 30 degrees C; not more than three Correct answer.
  4. 25 degrees C; not more than three

Explanation

Table 310.16 ampacities assume an ambient temperature of 30 degrees C (86 degrees F) and no more than three current-carrying conductors in a raceway or cable. Where the ambient temperature differs or the number of current-carrying conductors exceeds three, correction or adjustment factors must be applied.

Question 32General Electrical Knowledge and National Electrical Code Structure

Chapter 9, Table 8 of the NEC provides which of the following?

  1. The allowable percentage of conduit fill for conductors
  2. Conductor properties such as dc resistance and area Correct answer.
  3. The ampacity adjustment factors for ambient temperature
  4. The radii of conduit bends for various trade sizes

Explanation

Chapter 9, Table 8 lists physical and electrical properties of conductors, including cross-sectional area and dc resistance at 75 degrees C. These values support voltage-drop calculations and other design computations.

Question 33General Electrical Knowledge and National Electrical Code Structure

Class I hazardous (classified) locations may be classified by division or by zone. Requirements for Zone 0, Zone 1, and Zone 2 locations appear in:

  1. Article 503
  2. Article 502
  3. Article 505 Correct answer.
  4. Article 500

Explanation

Article 505 governs Class I, Zone 0, Zone 1, and Zone 2 locations, providing an alternative zone-based classification system to the division system of Article 500. Articles 502 and 503 address Class II and Class III locations, respectively.

Question 34General Electrical Knowledge and National Electrical Code Structure

Under Section 110.9, equipment intended to interrupt current at fault levels must have an interrupting rating that is:

  1. not less than twice the calculated continuous load current of the circuit
  2. based on the next higher standard rating above the calculated load current
  3. equal to the ampacity of the circuit conductors supplying the equipment
  4. at least equal to the available fault current at its line terminals Correct answer.

Explanation

Section 110.9 requires equipment that interrupts current at fault levels to have an interrupting rating at nominal circuit voltage at least equal to the fault current available at its line terminals. If the available fault current exceeds the rating, the equipment could fail violently when clearing a fault.

Question 35Wiring Methods, Materials, and Installation Requirements

Type UF cable supplies a detached garage on a residential property and is direct buried beneath a lawn. No GFCI protection is provided on the circuit. What is the minimum cover required over the cable?

  1. 24 inches Correct answer.
  2. 12 inches
  3. 30 inches
  4. 18 inches

Explanation

Table 300.5 requires 24 inches of cover for direct-buried Type UF cable installed in earth. The reduced covers of 12 inches and 18 inches apply only to residential branch circuits rated 120 volts or less, protected by GFCI, and limited to 20 amperes.

Question 36Wiring Methods, Materials, and Installation Requirements

Type NM cable is permitted to be installed in which of the following locations?

  1. In a buried raceway under a driveway
  2. Inside a dry attic space of a dwelling Correct answer.
  3. Inside a masonry wall exposed to weather
  4. In a poured concrete slab on grade

Explanation

Type NM cable is a dry-location wiring method and may be used in dry, protected spaces such as the attic of a dwelling. It is prohibited in wet locations, in masonry or concrete that is exposed to moisture, and in underground raceways.

Question 37Wiring Methods, Materials, and Installation Requirements

What is the maximum interval at which Type NM cable must be secured to the building structure?

  1. Every 8 ft
  2. Every 4 1/2 ft Correct answer.
  3. Every 10 ft
  4. Every 6 ft

Explanation

Type NM cable must be secured at intervals not exceeding 4 1/2 ft and within 12 in of every box that does not have a cable clamp. The support interval keeps the cable from sagging and from being damaged by contact with the structure.

Question 38Wiring Methods, Materials, and Installation Requirements

When calculating outlet box fill, how is a cable clamp inside the box counted?

  1. It is not counted at all
  2. As one conductor of the largest size present Correct answer.
  3. As two conductors of the largest size present
  4. As one conductor of the smallest size present

Explanation

Each cable clamp or fitting inside a box is counted as one conductor sized to the largest conductor in the box. The volume allowance protects against crowding that could damage conductor insulation.

Question 39Wiring Methods, Materials, and Installation Requirements

What is the minimum size copper conductor permitted for a 15-ampere branch circuit?

  1. 12 AWG
  2. 14 AWG Correct answer.
  3. 10 AWG
  4. 16 AWG

Explanation

14 AWG copper has an ampacity of 15 amperes at 60 degrees C and is the minimum size permitted for a 15-ampere branch circuit. Larger conductors are permitted but are not the minimum.

Question 40Wiring Methods, Materials, and Installation Requirements

The equipment grounding conductor of a branch circuit is required to be identified by which insulation color?

  1. Green or green with yellow stripes Correct answer.
  2. White or gray
  3. Black or red
  4. Orange

Explanation

Green, or green with one or more yellow stripes, is reserved for the equipment grounding conductor. White and gray identify the grounded conductor, and other colors are used for ungrounded conductors.

Question 41Wiring Methods, Materials, and Installation Requirements

Which wiring method is not permitted to serve as an equipment grounding conductor?

  1. Schedule 40 PVC conduit Correct answer.
  2. Intermediate metal conduit
  3. Rigid metal conduit
  4. Electrical metallic tubing

Explanation

Nonmetallic conduit has no conductive path, so a separate equipment grounding conductor must be installed inside the raceway. Rigid metal conduit, IMC, and EMT are all recognized equipment grounding conductors when installed with listed fittings.

Question 42Wiring Methods, Materials, and Installation Requirements

Conductors installed in a raceway that is direct buried underground must be listed for which condition?

  1. Damp location
  2. Any location
  3. Wet location Correct answer.
  4. Dry location only

Explanation

The interior of an underground raceway is a wet location, so the conductors must be listed for wet locations. Insulation marked only for dry locations can deteriorate when exposed to moisture.

Question 43Wiring Methods, Materials, and Installation Requirements

Where three or more conductors are installed in a raceway, the total cross-sectional area of the conductors may not exceed what percentage of the raceway interior area?

  1. 31 percent
  2. 40 percent Correct answer.
  3. 53 percent
  4. 60 percent

Explanation

Chapter 9 tables allow a maximum fill of 40 percent for three or more conductors, which permits pulling without damage. One conductor may fill 53 percent and two conductors may fill 31 percent of the raceway area.

Question 44Wiring Methods, Materials, and Installation Requirements

Electrical metallic tubing is run horizontally. What is the maximum spacing between supports for the EMT?

  1. Every 15 ft
  2. Every 10 ft Correct answer.
  3. Every 6 ft
  4. Every 12 ft

Explanation

EMT must be secured at intervals not exceeding 10 ft and within 3 ft of each box, cabinet, or fitting. Closer supports are required where the conduit is likely to be damaged or where the run is made up with specific fittings.

Question 45Wiring Methods, Materials, and Installation Requirements

The total number of bends between pulling points in a run of rigid metal conduit may not exceed which value?

  1. 180 degrees
  2. 270 degrees
  3. 360 degrees Correct answer.
  4. 540 degrees

Explanation

No run of raceway may contain more than the equivalent of four quarter bends, or 360 degrees, between boxes, fittings, or pull points. Additional bends would make it impossible to pull conductors without damage.

Question 46Wiring Methods, Materials, and Installation Requirements

Six current-carrying 12 AWG conductors are installed in a single raceway. What percentage of the conductor ampacity must be used after adjustment?

  1. 90 percent
  2. 75 percent
  3. 70 percent
  4. 80 percent Correct answer.

Explanation

A run containing four to six current-carrying conductors requires an 80 percent adjustment of the ampacity. Adjustment accounts for the heat that conductors bundled together cannot easily dissipate.

Question 47Wiring Methods, Materials, and Installation Requirements

Type NM cable is pulled through a hole bored in a wood stud less than 1 1/4 inches from the stud edge. What protection is required?

  1. A plastic bushing at the hole
  2. The cable must be run in conduit
  3. A 1/16-inch steel plate Correct answer.
  4. The hole sealed with fire-rated caulk

Explanation

Where a bored hole is closer than 1 1/4 inches to the nearest edge of a wood member, the cable must be protected by a steel plate at least 1/16 inch thick. The plate prevents nails and screws driven into the wall from penetrating the cable.

Question 48Wiring Methods, Materials, and Installation Requirements

Which statement about outlet and junction boxes is correct?

  1. They may be concealed above a permanently installed ceiling
  2. They must remain accessible without removing finish Correct answer.
  3. They may be buried in plaster if a cover is used
  4. They may be covered by floor finish if labeled

Explanation

Boxes must be made accessible so that splices can be inspected and serviced without damaging the building finish. Concealing a box behind a permanent finish makes the splice inaccessible and is prohibited.

Question 49Wiring Methods, Materials, and Installation Requirements

At least how much free conductor must be left at each outlet or junction box for making splices or terminations?

  1. 6 inches Correct answer.
  2. 4 inches
  3. 12 inches
  4. 3 inches

Explanation

A minimum of 6 inches of free conductor must be left at each box, with at least 3 inches extending outside the box opening. The slack allows splices and terminations to be made without pulling on the conductors.

Question 50Wiring Methods, Materials, and Installation Requirements

A box is installed in a wall having a noncombustible finish. The box may be recessed behind the finished surface by no more than which dimension?

  1. 1/4 inch Correct answer.
  2. 1 inch
  3. 3/8 inch
  4. 1/2 inch

Explanation

In a noncombustible wall finish, the box may be recessed up to 1/4 inch from the finished surface. In combustible finishes the box or fitting must be flush with the surface.